Talk:Apollo D-2/Temp

The Apollo D-2 spacecraft was a design proposal submitted in May 1961 by General Electric (GE)en to NASA in a manned lunar orbiter spacecraft feasibility study for the Apollo program, along with several other submissions. GE's three part design used a bullet-shaped command module (reentry cabin), with a separate mission module cabin and a cyllindrical propulsion module. NASA decided to use its own two part design by Maxime Faget, which used a cone-shaped command module, supported by a service module containing propulsion and supporting equipment. GE later entered the spacecraft procurement competition, losing to North American Aviation.

GE publicly presented its design to the American Astronautical Society in December 1961. Similarities in the basic mission-command-propulsion module design have been noted to the Soviet Union's Soyuz spacecraft designed by Sergei Korolev, leading to speculation that Korolev incorporated GE's basic concept. A Soyuz variant would have been used in the Soviet manned lunar programs.

Design
The Apollo D-2 design is notable in that it separates the descent module from the mission module for significant weight savings in the parachute and ablative heat shield. The D-2 design consisted of three modules, similar to the modern Russian Soyuz design: a lower engine module, the lightweight headlight shaped descent module with hatch, and upper mission module that held the heavy life support and avionics and could also be de-pressurized to double as an airlock.

By jettisoning the mission module during descent, it would significantly lighten the descent module, reducing the amount of heavy ablative heat shielding needed for descent. This lighter descent module meant that a greater payload of supplies such as oxygen, water or scientific instruments could be carried in to space using the Saturn V rocket. It also allowed for approximately 50% greater habitable (pressurized) volume than the final Apollo design. This contrasted sharply with the final Apollo design chosen by NASA, which descended and aerobraked back to earth the entire weight of the heavy life support and avionics system used during the bulk of the mission.

This modular three part design is particularly notable because of it's similarity to the Russian's manned spacecraft Soyuz, the unmanned Progress spacecraft, the Chinese Shenzhou spacecraft, and the planned Indian ISRO Orbital Vehicle.

Similarity to Soyuz
The Apollo D-2 is notable for it's similarity to the highly successful Russian Soyuz spacecraft, which was designed and built after George Arthur and Jacob Abel's presentation in in December 1961.

Apollo feasibility studies
In July and August of 1960, NASA's Space Task Group hosted a series of NASA-industry conferences to discuss post-Project Mercury manned spacecraft plans. On August 30, NASA presented plans to award three feasibility study contracts for the Apollo spacecraft, conceived as a three-man Earth orbital and circumlunar craft, with growth potential for manned lunar landings. A Request For Proposal was issued on September 12, and fourteen bids were received by October 9. On October 25, NASA awarded the $250,000, six-month contracts to Convair, General Electric, and the Glenn L. Martin Company. Meanwhile, members of the Space Task Group performed their own spacecraft design studies, to serve as a gauge to judge and monitor the three industry designs.

The requirements specification called for a command module (piloting and re-entry cabin), a separate mission module cabin, and a propulsion and equipment module. All three competitors supplemented the $250,000 contracts with their own money: Convair spent $1 million, GE $2 million, and Martin $3 million. On May 15 to 17, 1961, the contractors presented their study results to NASA. Martin studied three different command module shapes, including a conical capsule vehicle similar to the STG configuration. Convair proposed a lifting body concept.

Spacecraft procurement competition
On May 25, 1961, one week after presentation of the feasibility study results, President Kennedy proposed the Moon landing objective to the US Congress, and by the end of April, Apollo effectively entered the procurement phase.

Seeking professional recognition for their work, George Arthur and Jacob Abel publicly presented papers documenting their D-2 design in December 1961 at a special symposium of the American Astronautical Society in Denver, Colorado.